411 Prospective monitoring of exposure and lung function among cement production workers - An international study
这项纵向研究追踪了8个国家24家工厂的4998名水泥工人，发现胸廓气溶胶暴露水平越高，肺功能（FEV1）下降越快，且低于现行职业暴露限值的水平也会导致显著肺损伤。
<h3>Objectives</h3> In this longitudinal study we aimed to estimate the longitudinal fall in forced expiratory volume at one second (FEV<sub>1</sub>) associated with different levels of thoracic aerosol exposure in cement production workers. <h3>Methods</h3> 4998 workers in 24 plants in eight countries were included in the study. Personal measurements of thoracic dust (n = 6942) were performed in 24 plants for 8 job types in 2007, 2009 and 2011. Arithmetic mean (AM) exposure in job types and plants was estimated from mixed models taking year and seasonal variation into account. FEV<sub>1</sub> was measured by spirometry in the same years. The longitudinal change in FEV<sub>1</sub>/m<sup>2</sup> of standing height was analysed in mixed models allowing for age, sex, smoking, allergy, asthma, previous dust exposure, and use of airway protection, using estimated exposures multiplied by observational time. <h3>Results</h3> The AM exposure level among non-administration employees varied between job types and plants from 0.14 to 14 mg/m<sup>3</sup>. A longitudinal loss in FEV<sub>1</sub>/m<sup>2</sup> of 2.9 ml/m<sup>2</sup>*(yr*mg/m<sup>3</sup>) (95% Confidence Interval, CI, 2.5–3.2) was estimated, assuming linear relationships. Using exposure stratified in quintiles, losses per (mg/m<sup>3</sup>)*yr were 5.9 ml (CI 3.0–8.8) in the 0.14–0.61 mg/m<sup>3</sup> category (reference), 9.7ml (CI 7.6–12) in the 0.62–1.57 mg/m<sup>3</sup> category, 14 ml (CI 12–17) in the 1.58–2.27 mg/m<sup>3</sup> category, 18 ml (CI 15–20) in the 2.28–5.40 mg/m<sup>3</sup> category and 19 ml (CI 15–22) in the 5.41–14 mg/m<sup>3</sup> category. <h3>Conclusions</h3> FEV<sub>1</sub> loss increased with exposure indicating that cement aerosol exposure may lead to adverse lung changes. Interpreting the change in the lowest exposure category as the age effect, FEV<sub>1</sub> losses in all other categories are significantly greater. Assuming that the thoracic fraction is 45–50% of total dust, the second lowest exposure level (0.62–1.57 mg/m<sup>3</sup>) is well below the present occupational exposure limit of 10 mg/m<sup>3</sup> of total dust.